Exposure-based ecotoxicity assessment of Co3O4 nanoparticles in marine microalgae.

Abstract

The exposure-effect study was conducted to evaluate the effect of Co3O4 nanoparticles on Tetraselmis suecica. The growth suppressing effect has been observed during the interaction between nanoparticles and microalgae as indicated by 72 h EC50 (effective concentration of a chemical at which 50% of its effect is observed) value (45.13±3.95 mg/L) of Co3O4 nanoparticles for Tetraselmis suecica. Decline in chlorophyll a content also indicated the compromised photosynthetic ability and physiological state of microalgae. Further biochemical investigation such as increase in extracellular LDH (lactate dehydrogenase) level, ROS (reactive oxygen species), and levels of membrane lipid peroxidation in treated samples signifies the compromised cellular health and membrane disintegration caused by nanoparticles. Parallel to this, the cell entrapment, membrane damage, and attachment of nanoparticles on cell surface were also visualized by SEM-EDX (scanning electron microscope-energy dispersive X-ray) microscopy. The overall results of this study clearly indicated that Co3O4 nanoparticles might have toxic effects on growth of marine microalgae and other aquatic life forms as well. Hence, release of Co3O4 nanoparticles in aquatic ecosystem and resulting ecotoxic effect should be broadly addressed.